assume cs:code,ss:stack
stack segment
    db 8 dup (0)
    db 8 dup (0)
stack ends
code segment
main:
    mov ax,stack
    mov ss,ax
    mov sp,16
    mov ax,4
    call s

    mov ax,4c00h
    int 21h
s:
    add ax,ax
    ret
code ends
end main